Surface heat flux estimation with embedded fiber Bragg gratings measurements: Numerical study

J. Gaspar (1) , Y. Corre (2) , J-L. Gardarein (1) , M. Firdaouss (2) , D. Guilhem (2) , M. Houry (3) , G. Laffont (4) , C. Niliot (1) , M. Missirlian (2) , C. Pocheau (2) , Fabrice Rigollet (1)

1 IUSTI - Institut universitaire des systèmes thermiques industriels
2 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique
3 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
4 LCFO (CEA, LIST) - Laboratoire Capteurs Fibres Optiques (CEA, LIST)

4 probes with Fiber Bragg Gratings (FBGs) will be integrated in Plasma Facing Component (PFC) of the WEST lower divertor in order to measure the bulk temperature distribution in the poloidal direction (11 locations equally spaced). A 2D nonlinear unsteady calculation combined with the Conjugate Gradient Method (CGM) and the adjoint state is used in order to estimate the space and time evolution of the surface heat flux based on temperature measurements. Synthetic measurements are generated assuming optical projection of the heat flux taking into account physical effects such as heat flux decay length ( λq ) and power spreading factor ( S ) in the private flux region and geometrical effects such as surface chamfering and round leading edges of the component. The inverse method is applied on different synthetic measurements in order to evaluate the ability of using FBG measurements to characterize the heat flux poloidal profile.

Mots clés: optical projection; surface heat flux; Conjugate Gradient Method; Fiber Bragg Gratings (FBGs); bulk temperature distribution

Domaines: Thermique [physics.class-ph]; Traitement du signal et de l'image [eess.SP]; Physique Nucléaire Expérimentale [nucl-ex]; Optique / photonique

J. Gaspar, Y. Corre, J-L. Gardarein, M. Firdaouss, D. Guilhem, et al.. Surface heat flux estimation with embedded fiber Bragg gratings measurements: Numerical study. Nuclear Materials and Energy, 2017, 12, pp.1077 - 1081. ⟨10.1016/j.nme.2016.10.015⟩. ⟨hal-01794290⟩